Experimental Study on Strain Characteristics of Underground Pipe During Liquefaction

Many studies of liquefaction have been performed very actively from the 1964 Niigata earthquake. From the results of these studies, the mechanism of liquefaction phenomena became almost clear. Not much work, however, has been done on the dynamic behavior of the buried pipe during liquefaction. The liquefaction of soils usually causes large damages to the pipes. This study has experimentally investigated on strain characteristics of buried pipe during liquefaction. As a result of this study these are main findings as follows, (1) The large strains are caused when the excess pore water pressure rises and falls. (2) The generation factors should contain not only the resonance of the system with external exciting force but also the effects of degree of transmission of the input waves through the model ground, degree of transmission of the ground strains to the pipe and the effect of flexibility of the system. (3) On the assumption that the degree of dynamic strains during liquefaction can be obtained as the product of these factors, we can well explain the generation phenomena of the dynamic strains during liquefaction.